Oligonucleotide microarrays are based on the hybridization of labeled mRNA molecules to short length oligonucleotide probes on a glass surface. Two effects have been shown to affect the raw data: the sequence dependence of the probe hybridization properties and the chemical saturation resulting from surface adsorption processes. We address both issues simultaneously using a physically motivated hybridization model. Based on publicly available calibration data sets, we show that Langmuir adsorption accurately describes GeneChip hybridization, with model parameters that we predict from the sequence composition of the probes. Because these parameters have physical units, we are able to estimate absolute mRNA concentrations in picomolar. Additionally, by accounting for chemical saturation, we substantially reduce the compressive bias of differential expression estimates that normally occurs toward high concentrations.

BiFeO 3 and Bi 2 FeMnO 6 films were epitaxially grown on SrTiO 3 ͑001͒ substrates by pulsed-laser deposition, and their structural, magnetic, magneto-optical and optical properties were measured. In Bi 2 FeMnO 6 , Fe is mainly present in the 3+ valence state, while Mn shows multivalence states. Bi 2 FeMnO 6 exhibits low magnetization at room temperature and at 5 K indicating there is no significant B-site ordering. The BiFeO 3 film shows high optical transparency, while Bi 2 FeMnO 6 shows high absorption loss in the infrared. Densityfunctional theory modeling of BiFeO 3 , BiMnO 3 and Bi 2 FeMnO 6 was carried out by applying the generalized gradient approximation ͑GGA͒ and GGA+ U methods. The formation enthalpy of ordered Bi 2 FeMnO 6 is positive for several crystal symmetries and for ferromagnetic ͑FM͒ or antiferromagnetic ͑AFM͒ spin structures at 0 K temperature, indicating B-site ordering is not favored. The electronic structure calculations are consistent with the electronic and optical properties of these films.

Magnetic garnets with Bi3+ are the standard media of discrete Faraday rotation isolators for IR-laser∕fiber-optical transmission at 1.55μm wavelength. For monolithic integration with semiconductors, perovskites of generic formula A[B]O3 offer promising alternatives that involve combinations of select transition-metal ions in octahedral B sites. In this paper, two concepts are described. In both cases, the 180° B–O–B bonding of the perovskite lattice could provide superexchange fields large enough to maintain spin ordering at room temperature. One model proposes a quasiferrite arrangement with antiferromagnetic alignment between Fe3+ and Ni2+ charge ordered in the double perovskite compound {A3+A′4+}[Fe3+Ni2+]O6. The other concept relies on ferromagnetism through delocalization superexchange with the composition A23+[Mn4+Ni2+]O6. Where appropriate to enhance Faraday rotation, Bi3+ can be used for A3+.

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We derive the functional dependence of the specific Faraday rotation ⌰, optical absorption ␣, and magnetooptical figure of merit F ϵ͉⌰͉ / ␣ on the dielectric tensor elements of a uniaxial, magneto-optically active material in a wavelength regime of relative transparency. In addition, we calculate F as a function of Ͻ 2.2 eV for the diamagnetic transition of the octahedrally coordinated Fe 3+ in bismuth doped yttrium iron garnet ͑ 0 = 3.15 eV͒ and show that F achieves a local maximum value in this frequency regime at = 1.25 eV. We also discuss the implications of this result in rare-earth iron garnets for bulk magneto-optical isolators and in orthoferrites for thin film devices. Finally, we discuss the importance of controlling linear birefringence in thin film isolators and its impact on the usefulness of F.